/* ----------------------------------------------------------------------
 * Project:      CMSIS DSP Library
 * Title:        arm_cfft_radix2_q31.c
 * Description:  Radix-2 Decimation in Frequency CFFT & CIFFT Fixed point processing function
 *
 * $Date:        18. March 2019
 * $Revision:    V1.6.0
 *
 * Target Processor: Cortex-M cores
 * -------------------------------------------------------------------- */
/*
 * Copyright (C) 2010-2019 ARM Limited or its affiliates. All rights reserved.
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Licensed under the Apache License, Version 2.0 (the License); you may
 * not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an AS IS BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "arm_math.h"

void arm_radix2_butterfly_q31(
	q31_t *pSrc,
	uint32_t fftLen,
	const q31_t *pCoef,
	uint16_t twidCoefModifier);

void arm_radix2_butterfly_inverse_q31(
	q31_t *pSrc,
	uint32_t fftLen,
	const q31_t *pCoef,
	uint16_t twidCoefModifier);

void arm_bitreversal_q31(
	q31_t *pSrc,
	uint32_t fftLen,
	uint16_t bitRevFactor,
	const uint16_t *pBitRevTab);

/**
  @ingroup groupTransforms
 */

/**
  @addtogroup ComplexFFT
  @{
 */

/**
  @brief         Processing function for the fixed-point CFFT/CIFFT.
  @deprecated    Do not use this function. It has been superseded by \ref arm_cfft_q31 and will be removed in the future.
  @param[in]     S    points to an instance of the fixed-point CFFT/CIFFT structure
  @param[in,out] pSrc points to the complex data buffer of size <code>2*fftLen</code>. Processing occurs in-place
  @return        none
 */

void arm_cfft_radix2_q31(
	const arm_cfft_radix2_instance_q31 *S,
	q31_t *pSrc)
{

	if (S->ifftFlag == 1U) {
		arm_radix2_butterfly_inverse_q31(pSrc, S->fftLen,
										 S->pTwiddle, S->twidCoefModifier);
	} else {
		arm_radix2_butterfly_q31(pSrc, S->fftLen,
								 S->pTwiddle, S->twidCoefModifier);
	}

	arm_bitreversal_q31(pSrc, S->fftLen, S->bitRevFactor, S->pBitRevTable);
}

/**
  @} end of ComplexFFT group
 */

void arm_radix2_butterfly_q31(
	q31_t *pSrc,
	uint32_t fftLen,
	const q31_t *pCoef,
	uint16_t twidCoefModifier)
{

	unsigned i, j, k, l, m;
	unsigned n1, n2, ia;
	q31_t xt, yt, cosVal, sinVal;
	q31_t p0, p1;

	//N = fftLen;
	n2 = fftLen;

	n1 = n2;
	n2 = n2 >> 1;
	ia = 0;

	// loop for groups
	for (i = 0; i < n2; i++) {
		cosVal = pCoef[ia * 2];
		sinVal = pCoef[(ia * 2) + 1];
		ia = ia + twidCoefModifier;

		l = i + n2;
		xt = (pSrc[2 * i] >> 1U) - (pSrc[2 * l] >> 1U);
		pSrc[2 * i] = ((pSrc[2 * i] >> 1U) + (pSrc[2 * l] >> 1U)) >> 1U;

		yt = (pSrc[2 * i + 1] >> 1U) - (pSrc[2 * l + 1] >> 1U);
		pSrc[2 * i + 1] =
			((pSrc[2 * l + 1] >> 1U) + (pSrc[2 * i + 1] >> 1U)) >> 1U;

		mult_32x32_keep32_R(p0, xt, cosVal);
		mult_32x32_keep32_R(p1, yt, cosVal);
		multAcc_32x32_keep32_R(p0, yt, sinVal);
		multSub_32x32_keep32_R(p1, xt, sinVal);

		pSrc[2U * l] = p0;
		pSrc[2U * l + 1U] = p1;

	}                             // groups loop end

	twidCoefModifier <<= 1U;

	// loop for stage
	for (k = fftLen / 2; k > 2; k = k >> 1) {
		n1 = n2;
		n2 = n2 >> 1;
		ia = 0;

		// loop for groups
		for (j = 0; j < n2; j++) {
			cosVal = pCoef[ia * 2];
			sinVal = pCoef[(ia * 2) + 1];
			ia = ia + twidCoefModifier;

			// loop for butterfly
			i = j;
			m = fftLen / n1;
			do {
				l = i + n2;
				xt = pSrc[2 * i] - pSrc[2 * l];
				pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]) >> 1U;

				yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
				pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]) >> 1U;

				mult_32x32_keep32_R(p0, xt, cosVal);
				mult_32x32_keep32_R(p1, yt, cosVal);
				multAcc_32x32_keep32_R(p0, yt, sinVal);
				multSub_32x32_keep32_R(p1, xt, sinVal);

				pSrc[2U * l] = p0;
				pSrc[2U * l + 1U] = p1;
				i += n1;
				m--;
			} while (m > 0);                    // butterfly loop end

		}                           // groups loop end

		twidCoefModifier <<= 1U;
	}                             // stages loop end

	n1 = n2;
	n2 = n2 >> 1;
	ia = 0;

	cosVal = pCoef[ia * 2];
	sinVal = pCoef[(ia * 2) + 1];
	ia = ia + twidCoefModifier;

	// loop for butterfly
	for (i = 0; i < fftLen; i += n1) {
		l = i + n2;
		xt = pSrc[2 * i] - pSrc[2 * l];
		pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);

		yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
		pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);

		pSrc[2U * l] = xt;

		pSrc[2U * l + 1U] = yt;

		i += n1;
		l = i + n2;

		xt = pSrc[2 * i] - pSrc[2 * l];
		pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);

		yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
		pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);

		pSrc[2U * l] = xt;

		pSrc[2U * l + 1U] = yt;

	}                             // butterfly loop end

}


void arm_radix2_butterfly_inverse_q31(
	q31_t *pSrc,
	uint32_t fftLen,
	const q31_t *pCoef,
	uint16_t twidCoefModifier)
{

	unsigned i, j, k, l;
	unsigned n1, n2, ia;
	q31_t xt, yt, cosVal, sinVal;
	q31_t p0, p1;

	//N = fftLen;
	n2 = fftLen;

	n1 = n2;
	n2 = n2 >> 1;
	ia = 0;

	// loop for groups
	for (i = 0; i < n2; i++) {
		cosVal = pCoef[ia * 2];
		sinVal = pCoef[(ia * 2) + 1];
		ia = ia + twidCoefModifier;

		l = i + n2;
		xt = (pSrc[2 * i] >> 1U) - (pSrc[2 * l] >> 1U);
		pSrc[2 * i] = ((pSrc[2 * i] >> 1U) + (pSrc[2 * l] >> 1U)) >> 1U;

		yt = (pSrc[2 * i + 1] >> 1U) - (pSrc[2 * l + 1] >> 1U);
		pSrc[2 * i + 1] =
			((pSrc[2 * l + 1] >> 1U) + (pSrc[2 * i + 1] >> 1U)) >> 1U;

		mult_32x32_keep32_R(p0, xt, cosVal);
		mult_32x32_keep32_R(p1, yt, cosVal);
		multSub_32x32_keep32_R(p0, yt, sinVal);
		multAcc_32x32_keep32_R(p1, xt, sinVal);

		pSrc[2U * l] = p0;
		pSrc[2U * l + 1U] = p1;
	}                             // groups loop end

	twidCoefModifier = twidCoefModifier << 1U;

	// loop for stage
	for (k = fftLen / 2; k > 2; k = k >> 1) {
		n1 = n2;
		n2 = n2 >> 1;
		ia = 0;

		// loop for groups
		for (j = 0; j < n2; j++) {
			cosVal = pCoef[ia * 2];
			sinVal = pCoef[(ia * 2) + 1];
			ia = ia + twidCoefModifier;

			// loop for butterfly
			for (i = j; i < fftLen; i += n1) {
				l = i + n2;
				xt = pSrc[2 * i] - pSrc[2 * l];
				pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]) >> 1U;

				yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
				pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]) >> 1U;

				mult_32x32_keep32_R(p0, xt, cosVal);
				mult_32x32_keep32_R(p1, yt, cosVal);
				multSub_32x32_keep32_R(p0, yt, sinVal);
				multAcc_32x32_keep32_R(p1, xt, sinVal);

				pSrc[2U * l] = p0;
				pSrc[2U * l + 1U] = p1;
			}                         // butterfly loop end

		}                           // groups loop end

		twidCoefModifier = twidCoefModifier << 1U;
	}                             // stages loop end

	n1 = n2;
	n2 = n2 >> 1;
	ia = 0;

	cosVal = pCoef[ia * 2];
	sinVal = pCoef[(ia * 2) + 1];
	ia = ia + twidCoefModifier;

	// loop for butterfly
	for (i = 0; i < fftLen; i += n1) {
		l = i + n2;
		xt = pSrc[2 * i] - pSrc[2 * l];
		pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);

		yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
		pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);

		pSrc[2U * l] = xt;

		pSrc[2U * l + 1U] = yt;

		i += n1;
		l = i + n2;

		xt = pSrc[2 * i] - pSrc[2 * l];
		pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);

		yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
		pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);

		pSrc[2U * l] = xt;

		pSrc[2U * l + 1U] = yt;

	}                             // butterfly loop end

}
